PTEN gene (10q23.31) encodes PTEN–phosphatase and tensin homolog protein (403 amino acids; 47,166 Da), with antitumor function by preferentially dephosphorylating 3-position on inositol head groups and reversing the reaction catalyzed by PI3Ks, inhibiting cell proliferation and migration and tumor invasiveness and metastasis, by inactivating the transmission of biological signals through the PI3K–PKB/AKT pathway [14,86,88]. The gene discussed is PIK3CA; the disease is neoplasm.